1. Field of the Invention
The present invention relates to a damper device of a clutch for a torque converter, the damper device being housed inside a torque converter.
2. Description of the Prior Art
In prior art transmission torque converters such as shown in U.S. Pat. No. 4,240,532, a turbine inside a torque converter is positioned between a pump on one side opposing the turbine and an input case on the other side which connects the pump to an input shaft. The input shaft is connected to an output shaft through a clutch plate, which frictionally engages with the input case as it moves in the axial direction between the turbine and the input case. The clutch plate and the turbine are connected to each other via a plurality of circumferentially extending coil springs in a manner which allows relative rotation, so that the fluctuations in torque are absorbed by the springs when the clutch plate is engaged with the input case to connect the input case with the turbine.
In this prior art device, the springs are circumferentially arranged in pairs, each of which is housed in a pocket portion of a driving ring mounted on the clutch plate on the side of the turbine. The spring end surface supporting members, which are integral with the driving rings, are inserted in circumferential spaces between adjacent pocket portions while a torque transmission member extending from the turbine is positioned between paired springs in the respective pocket portions, thereby transmitting the torque via the springs. However, this prior art arrangement is disadvantageous in the following points:
(i) The axial dimension of the space for installing the springs between the clutch plate and the turbine is reduced by the thickness of the driving ring, which limits the diameter of each spring to a small value.
(ii) As the torque transmission member is placed at a circumferential position separate from that of the end surface supporting member, the total length of the springs that can be mounted on the driving ring is reduced by the length of the torque transmission member in addition to the length of the end surface supporting member.
(iii) As the diameter and the length of each spring is limited to by the reasons mentioned above in (i) and (ii), it is difficult to make the spring capacity large for enhancing the damper effect of the springs.